SYSTEME DE DEGIVRAGE A SERPENTIN D'ECHANGE THERMIQUE

REFRIGERATION COIL DEFROST SYSTEM

Abrégé français

Système de dégivrage (10) pour comptoir réfrigéré (11). Le système (10) comprend un conduit de dégivrage (14) conçu pour être placé à proximité du serpentin de réfrigération (12) d'un comptoir réfrigéré (11). Un échangeur de chaleur (13) comprend un boîtier (16) conçu pour être fixé sur le comptoir réfrigéré. Le boîtier comprend plusieurs ventilateurs (18) servant à diriger l'air ambiant dans le boîtier et à le faire sortir par un orifice d'échappement (20). Un serpentin d'échange thermique (22) est situé dans le boîtier (16) et est connecté au conduit de dégivrage (14) dans lequel circule un liquide, par exemple du glycol. Une pompe (28) assure la circulation du liquide de dégivrage dans le circuit (24, 25), et les vannes de régulation (26, 27) empêchent le flux du liquide en mode de non dégivrage. En mode de dégivrage, le glycol est réchauffé par l'air ambiant qui est réchauffé par convection dans le boîtier d'échange thermique (16), et l'air frais (9) généré par les gaines de sortie (20) est mélangé à l'air ambiant plus chaud. En outre, le système est éconergétique.

Abrégé anglais

A defrost system 10 for a refrigerated display
counter 11 is described. The system 10 comprises a
defrost conduit 14 which is adapted to be positioned in
close proximity to a refrigeration coil 12 of a
refrigerated display counter 11. A heat exchanger 13
has a housing 16 which is adapted to be secured above
the refrigerated display counter. The housing is
provided with a plurality of fans 18 for directing
ambient air into the housing and out through exhaust
port 20. A heat exchange coil 22 is provided in the
housing 16 and is interconnected with the defrost
conduit 14 and through which flows a liquid such as
glycol. A pump 28 circulates the defrost liquid
through the circuit 24-25 and control valves 26-27 are
provided to arrest the liquid flow in a non-defrost
mode. In the defrost mode the glycol is heated by the
ambient air which is convected through the heat
exchange housing 16 and the cool air 9 generated at the
outlet ducts 20 is mixed with hotter ambient air. The
system is energy efficient.

Revendications

-9-
CLAIMS:
1. A defrost system for a refrigerated display
counter, said system comprising a defrost conduit adapted to
be positioned in close proximity to a refrigeration coil of
said refrigerated display counter, a heat exchanger having a
heat exchange housing adapted to be secured in proximity to
said refrigerated display counter, a plurality of fans
secured to said housing for directing ambient air into said
housing and out through exhaust ports, a heat exchange coil
in said housing, conduit means interconnected opposed ends
of said heat exchange coil to opposed ends of said defrost
conduit to constitute a defrost circuit, a defrost liquid in
said defrost circuit, a pump is connected to said circuit to
circulate said defrost liquid through said defrost circuit,
control valve means to arrest said defrost liquid in said
defrost conduit during a non-defrost mode of said system,
said system when in a defrost mode circulating said defrost
liquid through said heat exchange coil in said heat exchange
housing where said ambient air convected by said fans warm
said defrost liquid to defrost said refrigeration coil, said
exhaust ports releasing cooled air above said refrigerated
display counter for admixture with warmer ambient air.
2. A defrost system as claimed in claim 1 wherein
said heat exchange housing is an elongated housing secured
above said refrigerated display counter, said exhaust ports
being provided on a top wall of said elongated housing.

-10-
3. A defrost system as claimed in claim 2 wherein
said fans are secured along a sidewall of said
elongated housing.
4. A defrost system as claimed in claim 1 wherein
said control valve means comprises a solenoid valve
connected adjacent one end of said defrost conduit and
a check valve connected adjacent another end of said
defrost conduit whereby to arrest said defrost liquid
therein during said non-defrost mode.
5. A defrost system as claimed in claim 1 wherein
said defrost liquid is a glycol liquid capable of
maintaining its liquid state during the refrigeration
mode of said refrigeration coil.
6. A defrost system as claimed in claim 2 wherein an
air convection duct is secured to said exhaust ports of
said heat exchange housing for converting said cooled
air to a remote location for cooling a space.
7. A defrost system as claimed in claim 1 wherein
said control valve means comprises a pair of solenoid
valves connected to an inlet and outlet of said heat
exchange coil for connection to a defrost conduit of a
further refrigerated display counter for defrosting a
cooling coil associated therewith, said cooling coils
of said refrigerated display counters being defrosted
independent from one another, one at a time.
8. A method of defrosting a refrigerated display
counter having a refrigeration coil, said method
comprising the steps of:

-11-
i) disposing a defrost conduit of a defrost
circuit in close proximity to said refrigeration coil,
said defrost circuit having a heat exchange coil
located in a heat exchange housing secured at a desired
elevated location, said housing having a plurality of
fans for directing ambient air into said housing and
out through exhaust ports,
ii) circulating a defrost liquid through said
defrost circuit by a pump during a defrost mode of said
system,
iii) heating said defrost liquid with said ambient
air as it is convected through said heat exchange coil
in said housing,
iv) exhausting cooled air from said exhaust ports
for admixture with warmer ambient air, and
v) defrosting said cooling coil with said warm
defrost liquid.
9. A method as claimed in claim 8 wherein said step
(iv) further provided the step of convecting said
cooled air from said exhaust ports to one or more
remote locations.
10. A method as claimed in claim 8 wherein there is
further provided the step of arresting said defrost
liquid in said defrost conduit during a non-defrost
mode of said system.
11. A method as defined in claim 8 wherein there are
two or more defrost circuits each associated with a
respective one of two or more refrigerated display
counters, said defrost circuits being connected to said
heat exchange coil in said heat exchange housing by
valve means, and wherein there is further provided the

-12-
step of independently defrosting said refrigeration
display counters one at a time.
12. A method as defined in claim 8 wherein said
desired elevated location is a top portion of said
refrigerated display counter.

Description

- CA 022l3880 l997-08-26
REFRIGERATION COIL DEFROST SYSTEM
TECHNICAL FIELD
The present invention relates to a defrost
system and particularly for defrosting the
refrigeration coil of a refrigerated display counter.
BACKGROUND ART
The prior art, as exemplified for example by
10 U.S. Patent Nos. 5,263,892, 5,249,433, 4,283,922,
4,285,204, 4,336,692, 4,188,794, 4,4944,158,
4,208,884, 4,304,098, U.K. Patent 2,133,129 and
Japanese Patent 54-34170, teaches that known defrost
systems are complex in design, utilize electric heating
15 elements systems which are energy consuming and costly,
utilizes heat air convection systems inside the
refrigerated display counter, they often require
maintenance and are not very energy efficient.
Furthermore, these systems are dedicated to defrost a
20 single refrigerating coil and therefore there is a need
to adapt a system to each refrigerated display counter
utilizing a refrigerating coil. This is also very
expensive and energy inefficient.
25 SUMMARY OF INVENTION
It is a feature of the present invention to
provide a defrost system for a refrigerated display
counter and which substantially overcomes the above-
mentioned disadvantages of the prior art.
Another feature of the present invention is to
provide a defrost system for a refrigerated display
counter and wherein a defrost liquid is pumped through
an ambient air heat exchanger to heat the liquid and
simultaneously defrost a refrigeration coil and wherein
35 the cool air extracted from the defrost liquid is

CA 022l3880 l997-08-26
released in admixture with hotter ambient air whereby
to cool the air and provide an energy saving.
Another feature of the present invention is to
provide a defrost system for defrosting a refrigerating
coil of a refrigerated display counter and which system
utilizes a heat exchanger which uses ambient air to
heat the defrost liquid and wherein the heat exchanger
may be adapted to a plurality of refrigerated display
counters.
Another feature of the present invention is to
provide a defrost system for defrosting a refrigeration
coil of a refrigerated display counter and which system
is easy to install, requires very little maintenance,
is inexpensive and energy efficient.
According to a further broad aspect of the
present invention there is provided a method of
defrosting a refrigerated display counter having a
refrigeration coil and which method substantially
overcomes the above-mentioned disadvantages of the
prior art.
According to the above features, from a broad
aspect, the present invention provides a defrost system
for a refrigerated display counter. The system
comprises a defrost conduit adapted to be positioned in
close proximity to a refrigeration coil of the
refrigerated display counter. A heat exchanger having
a heat exchange housing is adapted to be secured in
proximity to the refrigerated display counter. A
plurality of fans is secured to the housing for
directing ambient air into the housing and oUt through
exhaust ports. A heat exchange coil is provided in the
housing. Conduit means interconnect opposed ends of
the heat exchange coil to opposed ends of the defrost
conduit to constitute a defrost circuit. A defrost
liquid is provided in the defrost circuit. A pump is

CA 022l3880 l997-08-26
connected to the circuit to circulate the defrost
liquid through the defrost circuit. Control valve
means are provided to arrest the defrost liquid in the
defrost conduit during a non-defrost mode of the
system. The system when in a defrost mode circulates
the defrost liquid through the heat exchange coil in
the heat exchange housing where ambient air convected
by the fans warms the defrost liquid to defrost the
refrigeration coil. The exhaust ports release cooled
air above the refrigerated display counter for
admixture with warmer ambient air.
According to a further broad aspect of the
present invention there is provided a method of
defrosting a refrigerated display counter having a
refrigeration coil. The method comprises the steps of
disposing a defrost conduit of a defrost circuit in
close proximity to the refrigeration coil. The defrost
circuit has a heat exchange coil located in a heat
exchange housing secured above the refrigerated
counter. The housing has a plurality of fans for
directing ambient air into the housing and out through
exhaust ports. A defrost liquid is circulated through
the defrost circuit by a pump during the defrost mode
of the system. The defrost liquid is heated by the
ambient air as it is convected through the heat
exchange coil. Cool air from the heat exchanger is
exhausted through the exhaust ports of the heat
exchange housing for admixture with warmer ambient air.
The cooling coil is defrosted by the warm defrost
liquid.
BRIEF DESCRIPTION OF DRAWINGS
A preferred embodiment of the present invention
will now be described with reference to the
accompanying drawings in which

CA 022l3880 l997-08-26
FIG. 1 is a schematic diagram of the defrost
system of the present invention incorporated with a
display refrigerated counter;
FIG. 2 is a perspective view showing the
construction of the heat exchanger;
FIG. 3 is a top view of the heat exchanger of
FIG. 1 partly fragmented showing the heat exchange coil
therein, and
FIG. 4 is a fragmented side view showing a
convection duct secured to the top wall of the heat
exchanger housing for convecting the cooled air from
the heat exchanger to a remote location.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings and more
particularly to FIG. 1, there is shown generally at 10
the defrost system of the present invention which is
adapted to a refrigerated display counter 11 herein
schematically illustrated. The refrigerated display
counter 11 is provided with a refrigeration coil 12 to
cool the refrigeration counter and the foodstuff (not
shown) usually displayed therein. Essentially, the
defrost system of the present invention consists of a
heat exchanger 13 and a defrost coil or conduit 14
z5 which is secured in close proximity to the
refrigeration coil 12 whereby to defrost the coil 12
and melt ice 15 that is usually formed thereabout.
Although not shown, a drip pan is usually secured in
close proximity to the refrigerating coil whereby to
collect any evacuated water during the defrost cycle.
The defrost coil or conduit 14 is formed to adapt to
the cooling coil 11 and the area thereabout, although
it is herein illustrated as a single loop coil.
Referring now additionally to FIGS. 2 and 3, it
can be seen that the heat exchanger 13 has a heat

CA 022l3880 l997-08-26
--5 --
exchange housing 16 which is adapted to be secured in
proximity to the refrigerated counter 11 and as herein
shown secured to a top wall 17 of the refrigerated
display counter. The reason for this is two-fold.
Firstly, there is more hot air at the upper level of
the refrigerated counter to be drawn into the heat
exchange housing and secondly it is a convenient
location to release cold air for admixture with the hot
air whereby to reduce the air temperature and thereby
o produce a saving on the air conditioning needs of the
supermarket in which refrigerated counters 11 are
located.
As hereinshown, a plurality of turbines or fans
18 are secured to a sidewall 19 of the heat exchanger
housing 16 and a plurality of exhaust ducts 20 are
provided in the top wall 21 of the housing 16. A heat
exchange coil 22, having a plurality of fins or plates
23 connected thereto, extends into the heat exchange
housing 16 which is hereinshown as an elongated
rectangular-like housing. The heat exchange coil 22 is
formed as a loop and provided with an inlet 22' and an
outlet 22''.
The defrost conduit 17 is also provided with an
inlet and an outlet conduit 25 and 24 respectively.
These conduits interconnect to the inlet 22l and the
outlet 22'', respectively of the heat exchange coil 22
through valve means. The outlet conduit 25 may be
provided with an insulating jacket 34 to reduce heat
loss.
The valve means is constituted by a solenoid
valve 26 connected to outlet conduit 24 and a check
valve 27 connected to the inlet conduit 25. A pump 28
is connected to the inlet conduit 25 and circulates the
defrost liquid, herein glycol, through the defrost
35 circuit which is comprised of the heat exchange coil

CA 022l3880 l997-08-26
and the refrigerating coil interconnected in a loop.
In the non-defrost mode, the solenoid valve 26 is
inoperable whereby the glycol in the defrost conduit 14
is idle between the solenoid valve and the
unidirectional check valve 27.
In the defrost mode the solenoid valve 26 is
opened and the pump 28 is actuated whereby to circulate
the glycol through the defrost circuit. The cooling
coil circuit 33 is shut off. At the same time, the
10 fans 18 are actuated whereby to convect hot ambient
air, usually at a temperature of about 75~F. through
the heat exchange housing 16 and out through the
exhaust ducts 20 as a cooled air flow 9. Accordingly,
the glycol is heated by the ambient air and as it is
15 circulated past the defrost coil or conduit 14 will
defrost the cooling coil 11 and melt any ice formation
15 thereabout. As the glycol is warmed by the ambient
air convected by the fans 18, it cools the air which is
convected through the heat exchange housing 16 and this
20 cool air 9 is either exhausted directly upwardly to mix
with the warmer air above the heat exchange housing 16
to lower the temperature of the air and thereby to
provide an energy savings on the air conditioning
system of the supermarket.
As shown in FIG. 4, the cool air 9 released from
the exhaust duct 20 in the top wall 21 of the heat
exchange housing 16 may also be convected by a
convection conduit system 30 to a remote location where
the cool air 9 may be used more efficiently, if
30 necessary. An impeller fan 31 draws the cool air from
the collecting section 32 of the convection duct and
draws it away from the housing 16. Dampers (not shown)
may be provided at strategic locations along the duct
30'.

CA 022l3880 l997-08-26
As is also shown in FIG. 1, the heat exchanger
13 may also be connected to two or more refrigerated
display counters 11, 11', etc., through valves 33 which
may be controlled from a remote location whereby a
plurality of display counters may be defrosted
independently and sequentially. The defrost cycle of a
plurality of defrost counters, may be programmed so
that each counter is defrosted one at a time and one
after another. Accordingly, the defrost system of the
present invention is inexpensive, very energy
efficient, and may be automatically controlled.
Summarizing the method of operation of the
defrost system of the present invention, it consists
basically of disposing a defrost conduit of a defrost
circuit in close proximity to a refrigeration coil of a
refrigerated display counter. The defrost circuit has
a heat exchange coil which is located in a heat
exchange housing secured above the refrigerated
housing. The housing has a plurality of turbines or
fans therein for directing ambient air into the housing
and out through exhaust ports. A defrost liquid is
circulated through the defrost circuit by a pump during
a defrost mode of the system. The defrost liquid is
heated with the ambient air as it is convected through
the heat exchange coil inside the heat exchange
housing. The cooled air from the exhaust ports is
exhausted for admixture with warmer ambient air.
Simultaneously the cooling coil is defrosted by the
warm defrost liquid. The cool air may also be
convected from the exhaust ports to a remote location
for cooling space or for other use. The heat exchange
housing may also be connected to a plurality of
refrigerated display counters through valve means so
that a plurality of cooling coils can be defrosted
sequentially.

CA 02213880 1997-08-26
It is within the ambit of the present invention
to provide any obvious modifications of the preferred
embodiments descrihed herein, provided such
modifications fall within the scope of the appended
claims.

Dessin représentatif